This invention relates generally to portable tanks and more particularly to a sloped bottom structure of a portable tank adapted for liquid storage and transport.
A large tank for liquid storage generally has a bottom discharge. The construction of a tank having a bottom discharge generally requires affixing legs to the bottom of the tank so as to raise the discharge opening from the ground or the supporting surface upon which the tank rests. In order to provide complete drainage of tank contents, without requiring tipping of the tank, has often required difficult and complex bottom structures.
It is more convenient to connect hoses and fittings from the side of the bottom rather than trying to reach a central discharge underneath the bottom of a large tank or bin. However, conventional side discharge construction has also been proven to be difficult.
It is therefore desirable to provide a portable tank having a sloped bottom structure that presents a smooth interior surface sloped toward the discharge opening to allow full drainage from the tank. Such a portable tank having a sloped bottom structure is disclosed in my copending application Ser. No. 144,376, filed Jan. 15, 1988, commonly assigned.
In this copending application a sloped bottom is described requiring a plurality of bends in the bottom to produce the slope. It is an object of the present invention to provide a sloped bottom structure for a portable tank having simplified construction formed from a single sheet of plate material without a formed bend being required to produce the slope.
A portable tank having a sloped bottom structure according to the present invention has a generally rectangular bottom plate having a discharge opening therethrough. A single bend directed toward the bottom discharge opening in the plate forms the sloped inner surface of the bottom. The sides of the generally rectangular bottom plate are upwardly curved so as to merge with upwardly extending side wall portions of the plate which terminate in a substantially horizontal edge. This edge joins with vertical side walls of the tank.
The bottom structure has four feet, each positioned adjacent a corner of the generally rectangular plate. These feet are hollow elliptical cylinders and may be formed from sheet metal stock. Each foot has a horizontal bottom edge and a sculptured upper edge which is contoured to match the curvature of the bottom plate. The feet position the discharge opening at the lowest elevation of the bottom plate when the feet rest on a horizontal surface and the upper edge of the bottom plate is in a horizontal plane.
The sloped bottom of the present invention has a closed seam connecting the edge with the discharge opening which is formed from a divergent gap in the plate extending from the opening to the edge of the plate. This gap converges at the discharge opening so that when the gap is closed, the bottom plate at the discharge opening is moved downwardly thereby positioning the opening at the lowest point in the plate. Liquid in the tank will drain by gravity flow in the bend and along the bend to the discharge opening to ensure complete drainage of the tank contents without the necessity of tipping the tank.
The sloped bottom of the present invention is simply formed by taking a flat rectangular piece of material such as plate aluminum or steel and drilling, stamping, or otherwise forming a discharge opening through the plate near one edge, cutting or stamping a divergent gap in the plate running between the opening and the nearest edge of the plate, bending the sides of the plate upward to form upwardly extending wall portions, and bringing the sides of the gap together so as to mate in a closed seam. The bringing together of the sides of the gap bows the bottom of the plate outward at the discharge opening which essentially moves the discharge opening downward while at the same time positioning the edges of the upwardly extending wall portions of the plate in a substantially horizontal plane.
The sloped bottom thereby formed may be enhanced by pressing or stamping a single bend which radiates from the opening away from the nearest edge so that liquid in the tank will drain into the bend and then be channeled along the bend to the discharge opening.
Further objects, features, and advantages of the invention will become evident from a consideration of the following detailed description when taken in conjunction with the accompanying drawing and the appended claims .